基于平面波解构滤波的探地雷达绕射波高精度成像  

High-resolution GPR Diffraction Wave Imaging Based on Plane Wave Deconstruction Filtering

作　　者：李雄伟 高小伟 姜涛 Li Xiongwei;Gao Xiaowei;Jiang Tao(Xi′an Research Institute Co.Ltd.,China Coal Technology and Engineering Group Corp.,Xi’an Shanxi 710077,China)

机构地区：[1]中煤科工集团西安研究院有限公司,陕西西安710077

出　　处：《工程地球物理学报》2024年第5期755-763,共9页Chinese Journal of Engineering Geophysics

基　　金：陕西省自然科学基础研究计划重点项目(编号:2022JZ-16);天地科技股份有限公司科技创新创业资金专项项目顶层设计重点项目(编号:2020-TD-ZD003);国家自然科学基金(编号:42374176)。

摘　　要：探地雷达(Ground Penetrating Radar,GPR)依托其高精度、易部署等优势在近地表地球物理勘探技术中独树一帜。其应用范围涵盖岩土工程勘查、地质工程质量检测、极地冻土区域勘查、月球浅表探测等领域。勘探目标为小尺度地下地质异常体时,其产生的电磁波场响应能够直接反映在GPR数据体中,在利用回波数据构建的剖面上表现为绕射波。针对该波场进行偏移速度分析及偏移能够获得更直观的异常体成像结果。然而GPR生成的剖面中包含直达波、地表反射波、噪声等能够降低成像精度的不确定信号,导致后续处理解释工作存在偏差。因此通过分析GPR数据中不同类型的波场同相轴斜率差异,引入平面波解构滤波技术,估计剖面倾角的同时进行解构滤波,从而提取单纯绕射波场。最终利用分离出的绕射波记录进行偏移速度分析及偏移成像处理。新方法能够生成高精度的偏移速度模型和单纯绕射波偏移结果。利用两者能够更为精确地定位地下地质异常体,获取相关物性信息及尺度参数。理论合成数据及实际冻土地区资料测试进一步验证新方法的实用性及可行性。As an effective exploration approach in subsurface geological survey,ground penetrating radar(GPR)can be deployed easily and achieve non-destructive detection.Its application scenario covers geotechnical engineering,geological engineering quality inspection,polar permafrost region exploration and lunar probe.Due to the distinction of permittivity between small-scale anomalous bodies and background media,the generated electromagnetic response can be recorded in the acquired GPR data.From this unique wavefield,we can analyse the velocity and migration processing to gain a high-resolution image of geological anomalies.However,the conventional B-scan data contains plenty of waveform such as direct wave,reflection wave and noise,which lead to low-quality imaging result.To provide an accurate dataset and reasonable interpretation,we analyzed the characteristics of various wavefield appeared in the GPR B-scan profile.In virtue of slope discrepancies with different waveforms,this paper introduced plane-wave destruction(PWD)filters which can estimate the local slope of events and extract diffraction waveform from original profile.Pure diffractions profile allows us to build the migration velocity model and to migrate the dataset.The proposed method can output high-resolution velocity model and final migrated diffractions profile of GPR B-scan.With these supplements the scale,position,and permittivity of anomalous structures are estimated expediently.The high feasibility of proposed workflow has been embodied via a test of synthetic GPR data.Also,a real GPR data acquired in permafrost are used to illustrate the high performance of the method.

关 键 词：探地雷达 绕射波成像 平面波解构滤波 

分 类 号：P631.3[天文地球—地质矿产勘探]